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A229687 Odd squares whose binary reversal is also a square. 3
1, 9, 20457529, 143784081, 331130809, 4365905625, 5216450625, 20074072489, 1193532215121, 10036851273801, 36014509461681, 38767247532225, 41413201925481, 155991531977649, 320642706437001, 2543173099393689, 2696589987547401, 4665141483989281, 87463589042698969 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
The sequence of binary reversals that are squares is a permutation of a(n), it begins: 1, 9, 20457529, 143784081, 331130809, 5216450625, 4365905625, 20074072489, 1193532215121, 10036851273801, 38767247532225, 36014509461681, ...
A029983 is a subsequence (after zero). - Antti Karttunen, Dec 20 2013
LINKS
FORMULA
a(n) = A229766(n)^2.
PROG
(C)
#include <stdio.h>
#include <math.h>
int main() {
unsigned long long n, t, r, sr;
for (n=1; n<(1ULL<<32); n+=2) {
t = n*n;
r = 0;
while (t) r = r*2+(t&1), t >>= 1;
sr = sqrt(r);
if (sr*sr==r) printf("%llu, ", n*n);
}
return 0;
}
(Scheme) (define (A229687 n) (A000290 (A229766 n))) ;; Antti Karttunen, Dec 20 2013
CROSSREFS
Sequence in context: A259159 A340181 A131678 * A029983 A358814 A225775
KEYWORD
nonn,base
AUTHOR
Alex Ratushnyak, Dec 19 2013
STATUS
approved

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Last modified June 19 13:19 EDT 2024. Contains 373503 sequences. (Running on oeis4.)